I'm a student studying in 9th grade, I am making this fictional habitable planet named Darwin B for a planet making competition. It orbits a sun like star at a distance of 1.15 AU or 172 million kilometres in a near circular orbit. Its rotation period is 19 hours, 38 minutes. Its mass is 6.15×10^24kg and its radius is about 6,743 kilometres. I have to calculate its orbital period and density but I'm weak in maths and don't know how to. Please help.